Rectorseal 97043 SureSeal Trap Seal, 3.5", Black Sureseal protects against the spread of dangerous bacteria like salmonella and deadly infectious diseases like sars which are believed to be caused/spread by sewer gases Resistant to lime scale and microbiological growth Initial cost plus installation is much less expensive than alternative solutions Eliminates the need for complex, time consuming, and expensive repairs when trap primers fail. (No walls or floors to tear up to access the problem.) Reduces use of potable water - lowering water bills